青海沙蜥的两性异型和雌性繁殖

作者研究了青海沙蜥(Phrynocephalus vlangalii)形态特征的两性异形和雌体繁殖特征。蜥蜴于2005年5月初捕自西宁以西约150km的倒淌河,被检形态特征包括体色、体长、腹长、尾长、头长和头宽,新排卵雌体维持在实验室梯度热环境中直至产仔。成体两性异形显著,而性未成熟个体缺乏两性异形。最大的成年雄体和雌体分别为70.2mmSVL(snout-vent length)和82.8mmSVL。雄性成体具有相对较大的头长、头宽和尾长,雌性成体SVL大于雄体且具有相对较大的腹长。对4个形态特征进行主成分分析(特征值≥0.5)区分出2个主成分,共解释83.9%的两性相关形态特征的变异。去除SVL差异的影响后,尾长、头长和头宽在第一主成分有较高的正负载系数(解释57.8%的变异),腹长在第二主成分有较高的负负载系数(解释26.1%的变异)。实验室梯度热环境下的雌体于6月下旬至7月中旬产单窝、2-6个后代。窝仔数和窝仔重与母体SVL呈正相关,幼仔重与母体SVL无关。未在青海沙蜥中检测到后代数量与大小之间的权衡。

Sexual dimorphism and female reproduction in the Qinghai toad-headed lizard Phrynocephalus vlangalii

The Qinghai toad-headed lizard Phrynocephalus vlangalii is a viviparous agamid lizard.We collected lizards in early May 2005 from a population in Qinghai(northwestern China)to study sexual dimorphism in morphological traits and female reproductive traits.The examined morphological traits included coloration,body size,abdomen length,tail length,head length and head width.Newly ovulated females were maintained on the laboratory thermal gradients until parturition.Sexual dimorphism was evident in adults but not in sexually immature individuals.The largest male was 70.2 mm SVL(snout-vent length)and the largest female was 82.8 mm SVL.Adult males were larger in head size and tail length,whereas females were larger in body size and abdomen length.A principal component analysis on adults resolved two components(eigenvalues ≥0.5)from four SVL-free morphological variables,accounting for 83.9% of variation in the original data.The first component(57.8% of variance explained)had higher positive loading for SVL-free values of tail length,head length and head width.The second component had higher negative loading for SVL-free values of abdomen length(26.1% of variance explained).Females on the laboratory thermal gradients produced a single litter per breeding season stretching from late June to mid-July,with a litter size of 2-6 young.Litter size and litter mass were both positively correlated with maternal SVL,and neonate size(mass)was not.We did not find the trade-off between size and number of offspring in P.vlangalii.